1. Field
The present disclosure relates to a microelectromechanical (MEMS) film for a semiconductor device test socket, including a bump with improved contact property.
2. Description of the Related Art
In general, a surface mounting semiconductor device such as an integrated circuit (IC) device or an IC package includes a land grid array (LGA), a ball grid array (BGA), a chip sized package (CSP), or the like. Such a semiconductor device needs to be tested to confirm its reliability before shipping to a customer.
As an example of such a test, a burn-in test is often used before a semiconductor device is applied to an electronic apparatus, to investigate whether the semiconductor device meets a required condition by applying a temperature and a voltage higher than those under a normal operation condition to the semiconductor device.
Referring to FIG. 1, in the case of a test socket 10, in a general test process, a semiconductor device 2 is mounted on the test socket 10 and then coupled to a device under test (DUT) board (not shown) to perform a test, for verifying durability and reliability of the device.
For example, electrical characteristics of the device are tested through an electrical contact between the test socket 10 and a conductive solder ball (not shown) of the semiconductor device 2 in a state in which the semiconductor device 2 is accommodated in the test socket 10, and in this case, a contact assembly P including a contact wire or a contact pin 12 as a means for achieving the contact therebetween, in order to smoothly perform the test in a repeated manner while reducing contact resistance and physical damage.
With recent downsizing of electronic products, a contact terminal of the semiconductor device 2 incorporated in each of the electronic products is also downsized and a pitch between contact terminals is narrowed accordingly. Therefore, in many cases, a pitch between contact wires or contact pins 12 of the test socket 10, which has been normally used, is too wide to be used for a test of the downsized semiconductor device.
In addition, the contact wire or the contact pin 12 is integrally bonded with a test board of a test apparatus through a soldering process, and hence, when a problem occurs in the test socket 10, the entire assembly may be disposed because the test socket 10 can hardly be separated from the test board.
As an attempt to cope with these problems, Korean Patent No. 1469222 and Korean Patent No. 1425606 describe a contact assembly in which a contact is formed by a MEMS process in order to achieve a fine pitch.
Referring to FIG. 2, a test socket 20 includes a base film 22 enclosing a block 24 and a conductive bump 26 that is MEMS processed on an upper surface of the base film 22. The base film 22 and the block 24 constitute a contact assembly P together with the conductive bump 26 that is electrically connected to a conductive ball 34 of a semiconductor device 32.
However, the test socket 20 shown in FIG. 2 still has a problem that a contact between the bump 26 and the ball 34 is remarkably degraded for the following reasons.
Firstly, a vertical deviation h in the height of the ball 34 may cause a contact fail.
Secondly, although the base film 22 is formed of a flexible material, the base film 22 may be hardened when the bump 26 and the ball 34 are brought into contact with each other, causing a contact fail.
Thirdly, as a contact area of the bump 26 is flat, the contact is degraded, and hence an electrical connection may be failed though a physical contact is achieved, causing a contact fail.